The present invention relates to a method of enhancing transmission opportunity and a wireless device using the same, and more particularly, to a method and a wireless device capable of shortening an interframe space time of the wireless device.
As a demand for wireless service increases, a bandwidth of the wireless local area network (WLAN) system is required to be wider. For example, bandwidths of the WLAN systems complied with standards of IEEE 802.11a/g are 20 MHz, bandwidths of the WEAN systems complied with standards of IEEE 802.11n are 20 MHz or 40 MHz, and bandwidths of the WEAN systems complied with standards of IEEE 802.11ac are 20, 40, 80 MHz or even 160 MHz.
From another perspective, internet of thing (IoT), which connects devices through wireless connections, is getting popular recently. The devices under IoT, expected to provide low data rate transmission and consume low power, do not require such a wide operating bandwidth. Typically, a 5 MHz (or 10 MHz) bandwidth is sufficient for the devices under IoT. In some applications, the devices under IoT may be narrowband devices, which are originally configured to operate in a narrowband system (e.g., under a standard of IEEE 802.11j), and attempt to operate in a wideband WEAN system (e.g., under a standard of one of IEEE 802.11a/b/g/n/ac). However, the wideband WEAN systems (IEEE 802.11a/b/g/n/ac) are usually not compatible with the narrow WLAN system (IEEE 802.11j).
In detail, the narrowband WLAN system and the wideband WLAN system both perform a distributed coordination function protocol (DCF) under a carrier sense multiple access with collision avoidance (CSMA/CA) mechanism. That is, devices under either the narrowband WLAN system or the wideband WLAN system have to sense a status of a wireless medium before transmission. If the devices find that the wireless medium is continuously idle for a specific duration, i.e., a DCF interframe space (DIFS) duration, the devices are allowed to transmit data. Otherwise, if the wireless medium is found busy during the DIFS duration, the devices defer their transmission. However, the DIFS duration corresponding to the narrowband WLAN system is much longer than the DIFS duration corresponding to the wideband WLAN system. In addition, a slot time, which is related to a length of a contention window of a backoff mechanism within the CSMA/CA mechanism, corresponding to the narrowband WLAN system is longer than a slot time corresponding to the wideband WLAN system as well. Hence, devices under the narrowband WLAN system would hardly obtain a chance to transmit data.
Therefore, how to enhance a transmission opportunity is a significant objective in the field.